Arithmetical calculator.



M. G. BURNETT.

ARITHMETICAL CALCULATOR.

I APPLICATION FILED OCT- 30. T914.

Patnted Apr. 17,1917.

2 SHEETS-SHEET 1- Wirnesses. InvenTor.

% F Michael G. Burnefr M. G. BURNETT.

ARITHMETICAL CALCULATOR. APPLICATION FILED OCT- 30. i914.

Patented Apr. 17, 1917.

Z SHuTS$HEET 2 WiTnesses. Mw

MWKW MICHAEL G.

BURNETT, OF WATERTOWN, MASSACHUSETTS, ASSIGNOR OF FIFTY-ONE ONE-HUNDREDTHS TO MICHAEL BURKE, OF MARLBORO, MASSACHUSETTS.

ARITHMETICAL CALCULATOR.

Specification of Letters Patent.

Patented Apr. 17', 1917.

' Application filed October 30, 1914. Serial No. 869,480.

To all cvkom it may concern: I

Be it known that 1, MICHAEL BURNETT, a cltizen of the United States, residing at Watertown, county of Middlesex, State of' Massachusetts, have invented anlmprovement in Arithmetical Calculators, of which the following description, in connection with the accompanying drawing, is a-specification, like characters on the drawing representing like parts.

This invention relates to an improved mechanical calculator which functions accurately and rapidly to ascertain the arith-' metical result for a given multiplicand and multiplier.

The object of this invention is to provide mechanical means for quickly determining the correct number of dollars and cents resulting from the multiplication of a given number of hours by a given rate of wage per hour.

Another object is to provide an arithmetical calculator in which provision is made for a large number of unit rates of wage and for a large number of hour units entailing a proportionately large number of resultant amounts.

As these mechanical calculators are employed periodically it is highly desirable that they should be in such form that they may, when not in active use, occupy a space of small compass. Another object is, therefore, to construct a calculator which is small and .compact without impairment of efficiency, accuracy, legibility of characters, or loss of rapidity or'facility of manipulation.

A further object is to obtain such a calculator in which only the result'desired is presented to view-a decided advantage over the former instruments and one that insures accuracy and rapidity in the attainment of the correct result.

In order to afford an understanding of the invention, a selected embodiment of the same has been illustrated in the accompanying drawings and will now be described.

Figure 1 is a perspective view of the arithmetical calculator and shows the; foldable standard;

Fig. 2 is a front elevation partially broken away and showing the endless character bearing element; I

Fig. 3 is a sectional view on the line 3-3 of Fig. 4; but with the cylinders, fabric and idler removed in order to show the shutter A mechanism;

Fig. 1 is a sectional view on the line 4-4, Fig. 3;

Fig. 5 shutter and mechanism therefor; I

Fig. 6 is a perspective of the V-shaped is a section of a modified form of bar spring employed in the modified shutter mechanism. I

The calculator in this selected embodiment has a casingl, preferably of sheet metal or other light durable material. The front face of the casing is cut away and a rectangular opening therein provided which extends transversely nearly across the casing. The numeral plate- 2 is aiiixed above and adjacasing 1 and is positioned immediately be-.

bind the opening in the front face thereof.

The cross-bar 6 has a transverse slot-7, ex-

tending throughout its length, in which the slide'8 is adapted to travel. The helical spring 9, one end of which is attached to the side of the casing 1 and the other to the slide 8, normallyg holds the slide tothe left limit of its travel. 7

A window 10, consisting of a long planoconvex lens, extends transversely the opening and is secured to the top of the crossbar 6 and to the upper edge of the opening in the casing 1, It thus presents a glass surface with magnifying properties through which any characters, passed beneath the hours and wage rate characters, may be the more easily read.

The shutters 11 are vertically slidably positioned in front of the casing opening and in their normal position cover the window. A shoulder 12 outwardly, projects at the upper end of each a means for depressing the same. The lower end 13 of each shutter is inwardly bent and enters within the casing throu hthe opening and has secured'thereto the ower end of shutter and functions as.

cent the top edge of the opening and has the helical spring 14:, the upper end of which is attached to the cross-bar (3. The tension of each of the springs H operates to hold the respective shutters 11 in elevated position. A slot is cut in each shutter, providing a Series of cam surfaces and detents for the studs 16 secured to the slide 8. \Vhen a shutter is depressed the stud 16, rides up the cam surface provided in the shutter slot and thereby moves the slide to the right against the tension of the spring 5) until the lower end 13 of the shutter impinges on the top edge of the casing opening. The stud 16 has then reached the horizontal recess or detent 17 of the slot and the tension of the slide spring 9 draws the stud 16 within the recess and locks the shutter in this depressed position against the tension of the shutter spring 14. The portion of the window 10 covered bythe particular shutteris then exposed and a clearviewis had therethrough. Upon the depression of another shutter, its particular stud functioning in a similar man- .ner, the slide'S is again drawnto theright and the stud of the former shutter leaves the recess 17 of the former shutter and permits the tension of its spring 14: to elevate the shutter into normal position. The same cycleof operations being completed in the second shutter, another portion of the Window 10 is exposed and the former portion is again covered. The shutter mechanism thus automatically operates to close one shutter while another is opened and permits the exposure of but a single portion at a time.

The character-bearing fabric 18 is suit ably mounted to pass beneath the Window 10.

The fabric is subdivided into vertical columns corresponding in width to that of the individual shutters 11. These columns are further apportioned into horizontal rows, and correspond in vertical dimension to the length of the opening made by the loweringof a shutter from its normal posi-' tion. In the rectangles 19, created thereby,

are delineated characters representing, in

. column is adapted to pass before .thewindo'w 10 immediately beneath the abbreviation for the word hours (in the numeral plate 2. The fabric 18 is formed of a suitable flexible material and maybe mounted and actuated in any suitable manner so as to cause the successive rectangles 19 to pass before; and

adjacent the window 10. In this selected embodiment, the fabric is adapted to be actuated by the cylinders 20 and 21, revolu-. 'bly mounted in the casing 1. Perforations 22 are provided in the fabric, one series near each edge, ahd are adapted to engage-the t eth 23 of the cylinders 20 and 21.; These cylinders are revolubly mounted in the casing and their shafts 24 and 25 have secured on one end knurled nuts 26 and 27, respectively. by which means the cylinders are r0- tated as desired. The idler 28, journaled in adjustable brackets 29 secured to the side of the casing 1, serve the double function of retaining the fabric away from the front of the casing and of taking up any slack therein. The tension of the idler on the fabric is increased or diminish d by the positioning of the brackets by cans of the screw-threaded stud mountings. A gear 30 is afiixed to the shaft 25 of the lower cylinder and is revoluble therewith. A detent 31 is'secured to the side of the casing and its roller stop 32 is adapted to be normally held between the teeth of the gear 30 by the ten sion of the helical spring 33. As the teeth on the periphery of the gear 30 correspond to the teeth on the cylinders, the detent acts as an impositive lock-or detent and functions to accurately and definitely position the cylinder and hence the fabric at any desired point.

The arithmetical calculator is supported in operative position by means of the standard 34 apertnred near both ends to receive the shaft 24 of the upper cylinder. The standard is adapted to be folded, when the calculator is not in use, along the sides and bottom of the casing and, when in operative position, is secured against movement by any suitable means,in the form shown, by a leaf spring affixed to leach casing side and bearing against an arm of the standard.

The operation of the improved device is simple, rapid and the resultsare legible and certain. To avoid confusion and possible mistakes, it is highly desirable that several sums be not presented to view when the result of a single arithmetical computation is desired. This is eifectuated in this improved construction by means of the shutters. Each of the vertical columns of arithmetical results has a shutter corresponding thereto which, when in depressedposition, permits the disclosure of a single rectangle of the table bearing fabric. The scale, transversely afiixedto the casing above and adjacent the opening, bears thereon a series of numerals which, in this embodiment, represents different rates of wage per hour in fractions of one dollar. The fabric, as shown, bears in itsextreme left column a progressive series of whole numbers from one upward which represents, as indicated dnthe scale thereabove, the time element-- number of hours. To determine the amount due for work or labor, for example as shown in Fig. 1, for 10 hours, when the wage earned is at the rate of $.25 per hour, one rotates the cylinders which carry the fabric before the opening, stopping when the figure 10 appears under the Hrs. heading on the scale.

The shutter beneath the .25 rate on the scale is then depressed when there is disclosed the arithmetical result desired; Further, each rectangle of the fabric bears thereon three decimal fractions, representing, respectively, the amounts due for 1-, 11;, hours atthe specified rate per hour designated by the adjacent scale. This result having been noted, and it being desired, for example, to ascertain the amount due for a similar period of time at a wage rate of $.10 per hour, the shutter under this rate on the scale is depressed, as shown in Fig. 2, which causes the former shutter to rise to normal closed position, and the result desired is solely presented to view.

In Fig. 5 there is illustrated another form of shutter mechanism and means actuated by the depression of one of the shutters for releasing any and all of the remaining shutters which may be in depressed position. This mechanism, as shown, comprises a V-shaped bar 35 extending longitudinally the casing and having a free edge 36 adapted to engage a shoulder 37 of the shutter 11, the shoulder 37 being at the end of the cam surface 38. In this form of the device, the casing may be offset as at 39 to form a stop for the shutter 11 in its raised position and the shutter may be provided with an inwardly extending flange 4:0, projecting through the casing so that the same may be normally sustained in raised position by a spring ll attached to said shutter and to the inner side of the casing. It would be obvious that upon the depression of the shutter, the surface 38 will cause the portion 36 of the V-shaped bar to yield sufliciently to release any other shutter which may be secured in depressed position thereby. When a depressed shutter is released it will be drawn upwardly by its spring 4E1 until the shoulder 37 strikes against the flange portion 39 of the casing. The V-shaped bar 35 is preferably made of spring steel stock. 7 Portions of the bend at the V may be'cut through as at 4 2 in Fig. 6 to decrease the spring action of the free edge thereof if, in rigid steel stock, the spring action is too great when the shutter beingdepressed and the depressed shutter are distant the length of the bar. A piece of rigid and a stop, for the bottom of the shutter.

steel stock 43, in this modified construction, is preferably affixed transversely the free edge 36 of the bar 35. This reinforcement efl'ectuates the substantially uniform transmission, throughout the edge 36 of the bar, of the force of the cam surface 38 of ashutter upon a corresponding portion of the bar edge.-

The shutter may be formed of a piece of sheet metal, the ends being flanged in reverse direction to provide a hand piece for the top The vertical edges of the shutters, when made of thin sheet metal, may be inwardly bent to form broader vertical bearing edges for each other.

This is a simpler form of construction which may be more cheaply manufactured and it is to be understood that the claims hereto annexed are intended to cover broadly this construction as well as the form illustrated in the remaining figures.

Having fully described my invention what I claim as new and desire to secure by Letters Patent is:

1. In an arithmetical calculator, a casing having an opening therein, a movable element in said casing having a scale and having arithmetical results delineated thereon, a scale on said casing adjacent said opening, said scales coiiperating to indicate an arithmetical result, a plurality of shutters in said casing adapted to cover said arithmetical results, means for retaining each shutter normally in closed position and means actuated by the opening of one shutter to cause all other shutters to be closed.

2. In an arithmetical calculator, a casing having an opening therein, a movable element in said casing having a scale and having arithmetical results delineated thereon, a scale on said casing adjacent said Opening, said scales cooperating to indicate an arithmetical result, a plurality of shutters in said casing for covering said arithmetical results, a plurality of springs in said casing adapted each normally to retain a shutter in closed position, and means actuated by the opening of one shutter to cause all other shutters to be closed.

3. In an arithmetical calculator, a casing having an opening therein, a movable elesaid scales cohperating to indicate an arithmetical result, a plurality of shutters in said casing for covering said arithmetical results,

means for retaining each shutter in normal closed position, a spring controlled crossbar in said casing, a plurality of studs on said cross-bar, a cam surface in each shutter adapted each to engage one of said studs whereby when one shutter is opened all other shutters will be automatically closed.

4. An arithmetical calculator, including a casing having an opening therein, a plurality of vertically slidable shutters adapted normally to close said opening, means for normally retaining said shutters in closed position, a cam surface and a detent in each shutter, a bar in said casing adapted to traverse said casing, means tending to hold said bar to one side of said casing, a pluralitycof studs on said bar, said studs each being adapted to engage one of said shutter cam surfaces and detents whereby when one shutter is depressed said detentv retains the same in depressed open position and said,

bar automatically effectuates the release of all shutters and the return of the same to normal closed position.

.5. An arithmetical calculator, including a casing having an opening therein, a plurality of "ertically slidable shutters adapted normally to close said opening, means for normally retaining said shutters in closed position, means for retaining a shutter in depressed open position and for efl ectuating the release and return to normal closed position of all other shutters, comprising a bar in said casing adapted'to traverse said casing, a spring secured to said bar and to said casing whereby one end of said bar is normally held adjacent the casing side, a cam surface and a detent in each of said shutters formed by a slot and recess therein, a plurality of studs on said bar, one opposite each slot and adapted to engage said cam surface and detent whereby when a shutter is depressed its stud will engage the cam surface, transversely actuate the bar which functions to release any depressed shutter, and said stud will enter said recess and detain the depressed shutter in such position.

6. lln an arithmetical calculator a casing having an opening therein, a movable element in said casing having a scale and having arithmetical results delineated thereon, a

naaaraa scale on said casing adjacent said opening, said scales cooperating to indicate a single arithmetical result, a plurality of shutter-sin said casing adapted to cover said. arithmetical results, and spring actuated means operable when one shutter is opened to cause automatically the remaining shutters to.

close.

7. An arithmetical calculator including a casing having an opening therein, a plurality of vertically slidable shutters adapted normally to close said opening, a lower inwardly turned flange on each shutter, a spring secured to said flange and to a cross bar in said'casing whereby said shutters are two subscribing witnesses,

MICHAEL G. BURNETT Witnesses:

MAURICE M. .Moorz'n, THoMAs J. DRUMMOND.

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